O, o-dimethyl s-(1-succinimidoethyl) phos-phorodithioate and insecticidal compositions containing the same



United States Patent 3,316,145 0,0-DIMETHYL S-(l-SUCCHNIMIDOETHYL) PHOS-PHORODITHIOATE AND INSECTICIDAL COM- POSITIONS CONTAINING THE SAMEAlbert H. Haubein, Newark, Del., assignor to Hercules Incorporated, acorporation of Delaware No Drawing. Filed Jan. 11, 1965, Ser. No.424,843 6 Claims. (Cl. 167-33) This invention relates to insecticidesand more particularly to organophosphorus compounds having long residualactivity.

It is known that phosphorodithioates of many kinds have insecticidalactivity. It is also known in German Patent 930,446 that 0,0-dimethylS-(l-succinimidomethyl) phosphorodithioate is toxic to some insects andin U.S. 2,902,493 that 0,0-diethyl S-(Z-succinimidoethyl)phosphorodithioate is also toxic to insects. These insecticides arebiodegradable insecticides and are thus nonpersistent, but they do nothave very long residual activity. Biodegradable insecticides arenecessary on food crops since the insecticidal activity must be absentby the time of harvest. Biodegradable insecticides are desirable fromthe standpoint of avoiding possible contamination of rivers and streams.While biodegradability is desirable from the standpoint of safety, aresidual activity lasting for prolonged periods is particularlydesirable in those cases where the insects are controlled by contactwith surfaces which have been treated.

In accordance with the present invention, it has now been found that0,0-dimethyl S'(1-succinimidoethyl) phosphorodithioate is abiodegradable insecticide having a long residual toxicity.

The long residual toxicity of this compound is readily demonstrated byapplying 0,0-dimethyl S-( l-succinimidoethyl) phosphorodithioate at therate of 25 mg. per square foot of surface to the inner surface of anon-porous unwaxed paper drinking cup and leaving the cup exposed toambient conditions of about 78 C. and 50% relative humidity for a periodof time up to two months and determining the kill of adult mosquitoesplaced therein for one-hour periods from the time to time.

In this residual toxicity test procedure, a 0.25% aqueous emulsion of0,0-dimethyl S-(l-succinimidoethyl) phosphorodithioate was pipetted intoa non-porous, unwaxed paper cup in an amount sufficient to cover thesurface with 25 mg. per square foot and this emulsion was spread allover the inner surface until dry. Then the cups were allowed to standopen for 2 days at 78 C. and 50% relative humidity. Ten female, unfed,adult mosquitoes, anesthetized with CO were placed on an 18-meshstainless steel wire screen and covered by a treated cup, the screenbeing open to the air. The mosquitoes revived in a few minutes andwalked on the walls of the cup for an hour. They Were again anesthetizedwith CO and were placed in a 5-inch circular cage of l4-mesh stainlesssteel for 24 hours. The percent dead in 24 hours was then determined. Asecond group of mosquitoes was placed in the cup 7 days later and thetoxicity determined again. This was continued until an appreciable dropin toxicity was noted. The following data, showing the improvement inthe present invention, were obtained on 0,0-dimethylS-(l-succinimidoethyl) phosphorodithioate (Compound A) of this inventionand on 0,0-diethyl S-(2-succinimidoethyl) phosphorodithim ate (CompoundB) and 0,0-dimethyl S-(l-succinimidothioate of M.P. -97 C. Analysis:

a liquid concentrate.

methyl) phosphorodithioate (Compound C) of the prior art:

Days of Residual Toxicity Similar residual toxicity is shown againstother insects such as plum curculio on the skin of apples and against2-spotted mites on lima bean seedlings. Compounds A, B and C arebiodegradable when absorbed by the plant, as Well as when in contactwith unsterilized soil.

The following example, in which parts and percentages are by weight, isgiven to illustrate the invention.

Example 1 To 38 parts of N-vinyl succinimide in 40 parts of benzene wasadded 53.7 parts dimethyl dithiophosphoric acid in about parts ofbenzene dropwise over a 0.5 hour period. The resulting solution washeated at 80 C. under reflux for 6 hours, cooled and washed at 35 C.with water and 5% aqueous sodium bicarbonate solution. On cooling belowroom temperature, 39.3 parts crystalline product separated. Afterdistilling off the benzene and adding a little ether, an additional cropof 30.5 parts crystalline product was obtained. The product, oncrystallization from a mixture of benzene and petroleum ether, was0,0-dimethyl S-(l-succinimidoethyl) phosphorodi- P, 11.1%; S, 23.2%; C,34.19%; H, 5.36%.

The reaction between the N-vinyl succinimide and 0,0-dimethyldithiophosphoric acid takes place at a temperature within the range of25-l20 C. The reaction between N-a-chloroethyl succinimide and0,0-dimethyl dithiophosphoric acid, or a salt thereof such as theammonium salt, also yields the product of this invention. Solvents forthe latter reaction include acetone and acetonitrile in addition tobenzene or toluene.

The 0,0-dimethyl S-( l-succinimidoethyl) phosphorodithioate of thisinvention is useful as a toxicant in insecticide compositions for manytypes of insects and is used preferably as a dust or as an aqueousemulsion.

Dusts are formulated from a dust concentrate or from It is commonpractice for a formulator to dilute a dust concentrate with a clay orsimilar powdered solid to the desired dilution for application. The dustconcentrate, when compounded with a wetting Ialgent, is a wettablepowder, which is emulsifiable in the eld.

Aqueous emulsions are formulated by a formulator from a liquidconcentrate. The formulator will use either a liquid concentratecontaining the toxicant and a surface-active dispersing agent, or aliquid concentrate, water, and a surface-active agent. A liquidconcentrate containing a surface-active agent will be used by the man inthe field who wishes to prepare aqueous emulsions economically.

The concentrate is preferably a composition of the toxicant of thisinvention and a non-volatile adjuvant which is solid, as in the case ofdusts, or is liquid, as in the case here an aqueous emulsion is producedor in the case here a formulator mixes the liquid concentrate with dustv form a more dilute dust. A concentrate of toxicant 1d a volatileadjuvant such as a volatile organic solvent ill be useful also forcombination with a surface-active djuvant by a formulator ofconcentrates.

The concentration of the toxicant in a concentrate will e 10-90% in thecase where a volatile organic solvent used, and 25-90% where there is novolatile organic olvent.

The solid adjuvant of the composition is selected acording to theproperties desired from such solids as :lays, fullers earth,diatomaceous earth, rosin, petroleum iydrocarbon insoluble pine woodresins, and surfaceictive dispersing agents. The solid adjuvant willthus in nany cases have surface-active, spreading or sticking propertiesand, in some cases, will be used with water or organic solvent to aid inthe mixing process.

The liquid adjuvant of the composition is selected from the non-volatileliquids such as petroleum oils, paraffin, oils, lubricating oils androsin oils, and volatile liquids such as toluene, benzene, Xylenes,volatile petroleum fractions, acetone, methyl ethyl ketone, anddiacetone alcohol.

The concentrate containing a surface-active agent will contain usually0.01 to 2 times as much surface-active agent as toxicant and othercomponents to be dispersed in formation of an aqueous emulsion, andpreferably 0.05 to 0.5 times as much surface-active agent as material tobe dispersed. The concentrate which is a solution of all components suchas a concentrate of toxicant and surfaceactive agent which is soluble inorganic solvents preferably also contains a volatile organic solvent inan amount in the range of 0.1 to 10 times the weight of toxicant whennecessary to improve fluidity.

The concentrate of toxicant and liquid non-volatile adjuvant generallycontains 5-25% surface-active agent to aid in emulsification. Aconcentrate containing a surface-active agent is, by well knowntechnique, formed into water-in-oil or oil-in-water emulsions. For theformer, -25% surface-active agent is used and, for the latter, -20% isused. A concentrate containing toxicant, non-volatile adjuvant, andsurface-active agent is emulsified in the field without further dilutingbut it is, at times, advantageous to dilute this concentrate with oilcontaining a surface-active agent when it is desired to obtain dilutewater-in-oil, i.e., invert, emulsions. The surface-active agents whichare used are any of those anionic, cationic or non-ionic surface-activeagents well known in the art. See Chemistry of Insecticides, Fungicidesand Herbicides (Donald E. H. Frear, 2nd ed. 194-8, pages 280-7). Thesurface-active agents which are particularly suitable are thepolyoxyethylene compounds such as reaction products of alcohols oramines with ethylene oxide. Other surface-active agents and methods ofusing them for various types of emulsions are to be found in SurfaceActive Agents-Their Chem istry and Technology, Anthony M. Schwartz andJames W. Perry, Interscience Publishers Inc., New York, 1949,

and in Emulsions: Theory and Practice, Paul Becher, Reinhold, 1957.

A concentrate of equal parts each of acetone, 0,0- dimethylS-(l-succinimidoethyl) phosphorodithioate and Tween 20 (sorbitolmonolaurate polyoxyethylene derivative) was prepared and added todistilled water, with rapid stirring, to form emulsions of variousconcentrations from 0.05% to 0.0005% toxicant. A 0.025% emulsion gavekill of housefiies. An 0.0025% emulsion gave a 100% kill of Mexican beanbeetle. A 0.005% emulsion gave a 100% kill of pea aphids. A 0.0005emulsion gave a 100% kill of two-spotted mites. The residual activity,as indicated above, shows the superiority of the toxicant of thisinvention when applied to the habitats of mosquitoes. The toxicant ofthis invention, while high in residual activity on the habitats of manyinsects, is nevertheless not in the persistent class since it isbiodegradable, for example, in soil.

The 0,0-dimethyl S-(l-succinimidoethyl) phosphorodithioate of thisinvention can be used in combination with other insecticides wheredesired. The other insecticide need not be biodegradable since thebiodegradability of the present insecticide will act as an improver ofthe properties of the combination.

What I claim and desire to protect by Letters Patent is:

1. As an insecticidally active compound having a high residual activity0,0-dimethyl S-(l-succinimidoethyl) phosphorodithioate.

2. An insecticide concentrate comprising 0,0-dimethylS-(l-succinimidoethyl) phosphorodithioate as a toxicant and anon-volatile dispersing adjuvant therefor.

3. An insecticide concentrate comprising 0,0-dimethy1S-(l-succinimidoethyl) phosphorodithioate as -a toxicant and a solidnon-volatile dispersing adjuvant therefor.

4. An insecticide concentrate comprising 0,0-dimethylS-(l-succinimidoethyl) phosphorodithioate as a toxicant and asurface-active dispersing agent in an amount effective for dispersingthe toxicant in water.

5. An insecticide concentrate comprising 0,0-dimethylS-(l-succinimidoethyl) phosphorodithioate as a toXicant, an organicsolvent for the toxicant and a surface-active dispersing agent solublein said solvent in an amount effective for dispersing the toxicant inwater.

6. An aqueous emulsion comprising a major amount of water and a minorbut insecticidally effective amount of 0,0-dimethylS-(l-succinimidoethyl) phosphorodithioate and a surface-activedispersing agent.

References Cited by the Examiner UNITED STATES PATENTS 2,902,493 9/1959Lorenz 260-326.5

FOREIGN PATENTS 930,446 7/1955 Germany. 869,399 5/1961 Great Britain.

ALBERT T. MEYERS, Primary Examiner. JEROME GOLDBERG, Assistant Examiner.

1. AS AN INSECTICIDALLY ACTIVE COMPOUND HAVING A HIGH RESIDUAL ACTIVITY3,O-DIMETHYL S-(1-SUCCINIMIDOETHYL) PHOSPHORODITHIOATE.